Relay



June 21, 1932 J H. DERBY ETAL 1,863,836

RELAY flied Feb. 26. 1929 Z Sheets-Sheet l I INVENTOR5 June 21, 1932. J. H DERBY ETAL 1,863,835

RELAY.

Filed Feb. 26. 1929 2 Sheets-Sheet 2 Patented June 21, 1932 UNITED STATES PATENT OFFICE JOHN H. DERBY, 0F scARsnALE, NEW YORK, AND HENRY GEORGE LEAen, or BED BANK, NEw JERsEY, AssIe oRs 'ro AMERICAN FIRE PREVENTION BUREAU, or NEW YORK, Y., A CORPORATION or NEw YORK RELAY Application filed February 26, 1929. Serial No. 342,874.

This invention relates to relays and particularly to diiferentialrelays adapted to complete or to break one or more electrical circuits in response to currents or current im ulses having different characteristics.

iflerential relays are employed in circuits over which impulses of two different charactors are transmittedselectively to actuate various circuits or mechanism. The differential operation of such relays is effected in many instances by adjusting thetension of the springs or weights which retract the armatures so that both armatures will not respond to the same impulse. In some circuits two independent relays are employed, each of which is constructed or adjusted so as to be responsive to characteristic currents or impulses so that each will operate independently of the other.

The use of springs and weights for effecting the differential operation of relays is very unsatisfactory'for many purposes because of the fact that they must be carefully adjusted and there is danger of variation in the adjustment of parts so thatfrequent readjustment or. inspection is necessaryn On the other hand in circuitswhere the resistance or impedance of a circuit must be kept low it is often impossible or, objectionable to use two relays foryefiectingjthe differential operation desired. These difliculties have limited the sphere of usefulness of differential relays and have rendered them unsuitable for use in many electrical circuits where they would be of considerable value if the relays were sufficiently reliable, especially 1n circuits which are operated only occasionally and after long periods of idleness, for example in fire alarm circuits where reliability is of the utmost importance and inspection and operation ordinarily are infrequent.

One of the objects of the invention is to provide an improved relay in which the armatures are attracted in response to -magnetizing forces of difierent magnitude. I

Another object of the invention is to ut1- lize differences in-the magnetic resistance of elements of a magnetic circuit to effect the differential operation of a relay.

Other importantobjects and features of the invention will be apparent from a consideration of the following description of a preferred form of the invention as illustrated in the accompanying drawings.

' In the drawings:

Figure 1 is a perspective of a preferred form of relay embodying the present invention with the armatures in the attracted positions and with the coil removed toshow the construction more clearly;

Figure 2 is a side View of the armatures of the relay illustrated in Figure 1 in their attracted positions; t

Figure 3 is a View similar to Figure 2 but showing the armatures' in their released position;

Figure 4 is a vertical sectional View of the form of relay shown in Figure 1 with one of the armatures inthe attracted position and the other released;

Figure 5 is a vertical sectional View of the foiglm of relay taken on line 5-5 of Figure 4; an

Figure 6 is a vertical sectional View of the relay taken on the line 66 of Figure 4.

, I11 the form of the invention illustrated in the drawings, the differential relay comprises a U-shaped core 2 formed with legs 4 and 6. The core is made up of a plurality of laminated sections of soft iron secured together by means of rivets 7 and bolts 8 and secured to a support 9 by studs 10 and brackets 11. The coil 12 for energizing the core is shown applied to the leg 4 of the core and is connected by conductors 13 to a variable source of current, not shown, for su plying currents or current impulses of di erent magnitude to the coil. The face 14 at the outer end of the leg 4 acts as a pole piece toward which the armatures are attracted. a

The relay is provided with two armatures 16 and 18 formed of laminated soft iron. The armatures are pivoted on an iron pin 20 journaled in the soft iron members 21 secured to the leg 6 of the core. Thus the armatures 16 and 18 are both inmagnetic contact'with the leg 6 of the core and move about a common axis. The armatures are magnetically insulated from each other by means of brass or non-magnetic bushings 22. In some instances the pin 20, about which the armatures move may be formed of brass for insuring more nearly perfect magnetic insulation of the armatures from each other.

The pole face 14 toward which the armatures are attracted is provided with a copper shading coil 26 set into the end of the leg 6 of the core a sufficient distance to prevent the magnetizing coil 12 from being displaced on the core. The outer face of the shading coil projects a short distance beyond the pole face 14 so as to be engaged by the armatures when they are attracted toward the core.

The shading coil is only used when the relay is operated with alternating current in order to prevent chattering of the armature as the current is reduced to zero during each half cycle. The currents induced in the shading coil as the current in the coil 12 passes through zero hold the armature in the at tracted position so as to prevent chattering of the armature.

Each of the armatures is provided with a weight 30 for retracting the armature. The weights 30 are secured to the armatures by bolts 32 and 34. The bolt 34 carried by the armature 16 projects from the face of the armature and is provided with a nut 36 for engaging the shading coil projecting from the pole face 14 to limit the movement of the armature toward the core. The nut 36 is formed of iron having relatively high magnetic reluctance and having an area less than the area of the pole face 14.

The nut 36 carried by the armature 16 projects from the face of the armature and acts as a stop so that the armature 16, when in attracted position, is spaced from the face of the core a greater distance than is the armature 18 when the latter is in the attracted position. The movement of the armatures away from the face 14 of the core is limited by means of stop members 38 which are adjusted so that the air gap separating the armature 16 from the pole face 14 is greater than the air gap between the face of the core and the armature 18 when both armatures are in either their retracted or attracted positions. Therefore the armature 16 presents higher magnetic resistance to the magnetic circuit in either the attracted or retracted position than does the armature 18. F or this reason the armature 16 is subjected to a smaller magnetic force than the armature 18 and is released when the magnetic force is higher than is necessary to retain the armature 18.

The magnetic flux in the core 2 produced by a comparatively weak current through the coil 12 causes the armature 18 which is closer to the face 14 of the core to be attracted until it engages the shading coil 26. The armature 16 being separated from the face of the core by a larger air gap is not attracted to the face 14 of the core by a weak magnetizing force resulting from a weak current or impulse in the coil 12. However, if the current in the coil 12 should be increased so as to increase the attracting force applied to the armature 16, the latter will be attracted to the face of the core and will remain attracted until the current through the coil drops below a predetermined minimum. Because of the fact that the armature 16 when in attracted position is spaced from the face of the core a greater distance than the armature 18, the armature 16 will be retracted by its weight 30 when the current through the coil 12 and the induced magnetic flux is decreased and the release of armature 16 will take place before thearmature 18 is retracted. i w I If the coil 12 should be energized by direct current the shading coil 26 may be omitted and both armatures 16 and 18 provided with stops formed of fiber or other non-magnetic material. In this case the stop carried by the armature 16 should project from the face of the armature a greater distance than the stop carried by the armature 18. I

The armatures are each provided with a longitudinally-extending conducting member 40, to one end of which is connected an electrical conductor 42 and the opposite end of which is bent at right angles to the armature so as to form an arm 44. Thearm 44 carried by the armature 16 is provided with a contact member 46 for engaging a complementary contact member 48carried by one of the brackets 11. The arm 44 carried by the armature 18 is provided with a similar contact50 forvengaging a similar contact 52 carried by the other bracket 11. The stationary contacts 48 and 52 are shown as adjustable and preferably are provided with rounded surfaces over which the contact inembers 46 and 5 0 slide with a wiping action when the armatures are attracted and retracted.

The c ontacts 46 and50 carried by the arms 44 secured to thearmatures 16 and 18 are n shown in positions which will causethe circuit through the contacts 46 and 48 to be completed when the armature 16 is attracted to the core, whereas the contacts 50 and 52 will be broken when the armature 18 is attracted to the core.

The relay may be designed and constructed in various forms particularly adapted for various uses. The type of relay illustrated is particularly useful in connection with fire alarm circuits such as that shown and described in the Patent No. 1,536,192, dated May 5, 1925, wherein a small current iscontinuously passed through the trouble circuit under normal conditions. The normal current through this circuit is notsufiicient to create a magnetic force'suflicientto attract the armature 16 so-thatthe latter remains in the retracted positionbut the current is sufiicient to attractithe armature 18 to the core so that the trouble alarm circuit is held open. In this position of the armatures the contacts between the members 46 and 48 and 50 and 52 are broken. If a break should occur in the circuit so that the current is considerably decreased or the circuit broken the relay armature 18 will be released to cause the contact members 50 and 52 to engage and give a trouble signal. If the re.- sistance at the end of the circuit is cut out either automatically or manually, the current through the coil 12 will be increased and the core magnetized with a current or current impulse of greater magnitude so that the armature 16 will be attracted and a circuit will be completed through the contact members 46 and 48 to actuate an alarm.

The present invention is capable of use with many circuits other than that suggested. The particular requirements of various circuits and uses for the relay may render it necessary or advisable to change the form and construction of the relay in some instances, therefore, it should be clearly understood that the invention is not limited in its construction or use to the example described except as defined by the claims.

What is claimed as new is 1. A relay adapted to control a plurality of circuits each in response to a different degree of energizing of the relay which comprises an electromagnet, armatures magnetically connected to one pole of the electromagnet and movable toward and away from the other pole of the electromagnet within its magnetic field, circuit closing contacts associated with each of the armatures so as to be closed by movement of the armature in one direction and opened by movement in the other direction, said armatures being so designed and proportioned that when all are in the attracted position one is held or dropped accordingly as the current exceeds or falls below a critical value for which the relay is designed to respond. V

2. A relay adapted to control a plurality of circuits each in response to a different degree of energizing of the relay which com- I prises an electromagnet, armatures magnetically connected to one pole of the electromagnet and movable toward and away from the other pole within its magnetic field, and contacts associated with each of said armatures adapted to be operated by the movements of the armature to open and close a circuit, said armatures being so designed and positioned that one armature is attracted by a current below a given value and another is attracted by a current for which the relay is designed and above the given value and both are designed and proportioned so that above the given current value both will be held in the attracted osition.

3. A re ay adapted to control a plurality of circuits each in response to a different degree of energizing of the relay which comprises an electromagnet, armatures magnetically connected to one pole of the electromagnet and movable toward and away from the other pole within its magnetic field, and contacts associated with each of said armatures adapted to be operated by the movements of the armature to open and close a circuit, said armatures being so designed and positioned that one armature is attracted by a current below a given value and another is attracted by a current for which the relay is designed and above the 'ven value.

Signed at New York, ew York, this 20th day of February, 1929.

JOHN H. DERBY.

HENRY GEORGE LEACH. 

